Background. The metabolic syndrome (MetS) is highly prevalent in the growing U.S. Latino population. We hypothesize that MetS, with or without diabetes, is associated with progressive disability in older Mexican Americans. Methods. Data from Mexican Americans 60-98 years old participating in the Sacramento Area Latino Study on Aging (SALSA) were analyzed from baseline through 3 years (3 years of follow-up). Disability was assessed by self-reported limitations in activities of daily living (ADLs), instrumental ADLs (IADLs), and mobility/strength tasks. MetS (46% of sample) was defined by National Cholesterol Education Program (NCEP) Adult Treatment Panel III criteria. Diabetes (DM, 33%) was defined by fasting blood sugar > 125 mg/dL, physician diagnosis, and/or medication use. Four metabolic groups were defined: MetS with diabetes (MetS+DM+, n = 402); MetS without diabetes (MetS+DM-, n = 330); diabetes without MetS (MetS-DM+, n = 125); and neither (MetS DM-, n = 749). Generalized estimating equation (GEE) regression models were used to evaluate the effect of metabolic group on physical limitations and disability changes over time. Results. Diabetes, with or without MetS, was associated with a higher percent rate of increase over 3 years in ADL and IADL disability than was no diabetes, even after controlling for demographics, body mass index (BMI), and incident disease. The mean ADL score had a 35% higher rate of increase (higher = more impairment) for the MetS+DM+ group and 68% higher for the MetS-DM+ group. Results for IADL were similar. The baseline MetS, without or with diabetes, was associated with a significantly higher rate of increase in mobility/strength limitations (8% and 36.5%, respectively). Conclusions. In older Mexican Americans, MetS is associated with progressive limitations in mobility and strength. Preventing progressive mobility/strength limitations may require assessing and treating these impairments in people with MetS regardless of the presence of diabetes. However, preventing the progression of MetS without to MetS with diabetes may be important to limit the progression of ADL and IADL disability found in people with MetS and diabetes.